DESCRIPTION: Females produce speech with a higher fundamental frequency (f0, voice pitch) as compared to male-produced speech. This higher f0 results in relative under sampling of the spectral envelope which should, in turn lead to lower intelligibility. However, excerpts from natural speech produced by females is as or more intelligible than male speech. This application proposes a series of complementary speech perception and production experiments designed to uncover gender-specific acoustic attributes that lead to this enhanced intelligibility. In particular, females have been characterized as speaking slower, with a more "breathy" voice, and with greater pitch excursions or "swoopiness." While these descriptions have in the past been considered derogatory, they may, in fact, be signs of adaptive production by females to compensate for the negative effects of a high voice pitch. In order to test this possibility, a large database of speech samples from oral reading will be analyzed for gender differences in breathiness, dynamic f0 range and speaking rate. A large number of acoustic measures theoretically related to breathy phonation will be computed. Using Principal Components Analysis. A composite acoustic measure of breathiness will be developed. Breathiness will then be analyzed by gender and by vowel. These measures can serve as much-needed gender-specific normative data on production. These data may be important for more sensitive diagnoses of vocal pathology, for synthesis of realistic-sounding female speech, and for the creation of gender-specific templates for automatic speech recognition. In addition, any gender differences uncovered by these analyses will form the basis of perception experiments designed to test their consequences on intelligibility. It is predicted that females produce high tense vowels as more breathy than similar lax vowels and that this pattern increases the size of the resultant vowel space. To test these predictions, synthesized vowels will be created to mimic various acoustic aspects of male- and female-produced speech. Listeners will attempt to identify these stimuli when presented in babble noise. If the female pattern of breathiness is adaptive, then the resulting vowels should be easier to identify than vowels that do not vary in breathiness. Similar predictions are made for "swoopiness." If the perception tasks reveal that gender-specific acoustics can enhance intelligibility, then these data may be important for development of signal processing techniques for enhancing communication. This series of perception-production studies will be interpreted within a framework that proposes that speakers faced with individual intelligibility challenges vary their speech production in ways that enhance the auditory cues to phonetic identification, thereby aiding the listener.